Controlling mechanism.



D. LARSON.

CONTROLLING MECHANISM.

APPLICATION FILED JULY 18, 1911 1,016,834. Patented Feb. 6, 1912.

mums-SHEET 1.

D. LARSON.

CONTROLLING MECHANISM.

APPLICATION FILED JULY 18,1911.

1,016,834, Patented Feb. 6, 1912.

3 SHEETSSHEET 2.

q/vi l'weooeoz I MM Svwentoz D. LARSON. OONTROLLING MECHANISM.

APPLICATION FILED JULY 18, 1911.

Patented Feb. 6, 1912.

3 SHEETSSHEET 3.

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DAVID LARSON, OF YONKERS, NEW YORK, ASSIGNOR TO OTIS ELEVATOR COMPANY, OF {JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

CONTROLLING MECHANISM.

Specification of Letters Patent.

Application filed July 18, 1911. Serial No. 639,081.

To all whom it may concern Be it known that 1, DAVID LARSON, a sub- 'ject of the King of Sweden, residing at Yonkers, in the count State of New York, ave invented a new and useful Improvement in Controlling Mechanism, of which the following is a specification.

My invention relates to a system of control for electric motors, more particularly to the control of motors for elevator or other hoisting apparatus.

- One object of my invention is to prevent the motor from either attaining an unsafe speed or running at too slow a speed.

A further object is to prevent a reverse current in the motor field when the motor is driven by the load.

Other objects of the invention and the exact nature thereof will appear hereinafter.

A compound wound motor for hoisting apparatuskpossesses the features of heavy starting torque, and constant speed when the shunt field. alone is excited. It is the usual practice to excite both fields in starting and to short-circuit the series field after the motor is accelerated. Winen the load drives the motor as a generator a reverse current will flow in the-series field windin s, which tends to weaken the total fled strength, and this may, under certain condi tions, reach a dangerous limit.

My invention relates particularly to the control of the series field.

In the accompanying drawings,.ligore 1 is a top or plan view of an accelerating magnet constructed in accordance with the rinciples of my invention; Fig. 2 is an en elevation view of the same; and Fig. 3 is a wiring diagram showin circuit connections for an. elevator installation utilizing my system of control. Y

Referring more particularly to Figs. 1 and 2, the accelerating magnetcomprises a magnet winding secured to a magnet frame 11 which is fastened to a switchboard or support 12 and provides also a core 18 for the magnet winding. On this magnet frame 11 contact arms 14: are mounted by the pivot 15 and are arranged to be drawn up to the magnet core 13 in accordance with the encrgization of the magnet. These 'con tact arms 14 are formed with enlarged portions or weights 14 so disposed as to cause of Westchester and the arm to fall back when the magnet is not energized, adjustable stops 16 being located on the magnet frame 11 to limit the back- Patented Feb. 6,1912:

ward movement of each arm. At the contactends of the arms l-arecontacts 1, 2, 3, 4 and 5 each insulated from its carrying arm and having a terminal connection 18 for an electrical conductor. A contact holder 21 secured to the support l2 and comprising contact holding members clamped together by screws 23, or other. fastening devices is adapted to hold stationary contacts 013- poslte the movable contacts 1, 2, 3 and 4. A projection 24 of the contact holder 21 supports a contact 25. A contact 26 for making connection with the contact 25, is

- held by a movable yoke-shaped member 27 formed on the upper end of an arm 28 pivoted on the rod 15. This member 27 also holds a contact 20 in position to make connection with the contact 5, the form of the said member and the disposition of the contacts being such that only one pair of contacts and 26, or 20 and 5, are together at a time. When the accelerating magnet is deenergized, a coil spring 31, interposed between the yoke 27 and the stationary arm 24, holds said yoke in its forward position with the contacts 25 and-26 in engagement.

When the magnet wirldin'g 10 is energized with a gradually increasingrcurrent the contact arms are drawn up in succession, the one opposite the contact 20 being the last one to be so drawn up. When connection is made with'contact 20 the member 27 is thrust back separating contacts 25 and 26. It is to be understood that the successive operation of the contact arms is regulated by the adjustment of the stops v16. Both the holder 21 and the supporter 27 are electrical conductors. v

An embodiment of my invention diagrammatically shown by Fig. 3, will now be explained. In this figure a car 0 and counterweight W are shown connected to a driving motor M. The motor receives current from the mains and through a main switch S and one of the reversing switches R and R, the reversing switches being controlled by the switch K in the elevator car C. An electro- 10 connected through the auxiliary contacts 7* of either reversing switch across the armature of the motor M controls the starting resistance X and with the aid of the device D controls the series field As soon as s a reversing switch is closed, the shunt field l3 and brake winding 34; are connected across the mains, the magnet winding 10 is connected across the motor armature and the motor armature receives current from the mains through he series field E and the starting resistance X. This circuit through the armature is traced from the negative lead 35, by Way of conductor 36, series field E, conductor 3 starting resistance X, con ductors 38, 39, through reversing switch contact, the motor armature, and another 1 versing switch contact to the positive lead 40. The motor starts with all the armature resistance X and the series field in series with the armature, as the motor speeds up, the accelerating magnet winding 10 which is connected across the motor armature has the connter-electro-motive force of the motor applied to it and the accelerating magnet contacts 1, 2, 3, 4t and are drawn up in regular succession, thereby short-circuiting portions of the sectional resistance. The terminals of the so its field i con- 1 nected to the contacts 41- and 5, and as soon 1, and a portion of the starting resistance X to the conductor 39, and parallel with the path through the member 27 from conductor 35 to conductor 3.), the resistance of the first-named path so greatin comparison to the latter that no appreciable current flows through the series field. The resist. ance of a series field alone is so small that it is frequently found in 'n-actice that the resistance of the contacts in a parallel circuit are equal to or greater than the resist ance of the series field.

it is evident that the path through the member 2'? may be of thesmallest resistance, for there is onl one contact connection to be made andin comparison with the two contact connections and the portion of starting resistance in series with the series field, constitutes, substantially a short-circuit around the series field. This connection, however, does not sever the series field connections, and there can be no danger of an open armature circuit by reason of the :EaiL ure of the device D tooperate; /V hen the Although a path may be" series field is short-circuited the motor operates .at constant speed as a simple shunt motor,

If the motor is being driven by a load the accelerating device Will be energized when a certain speed is attained, and the device D operates to short-circuit the series field thus preventing the series field from Weakening the magnetism set up by the shunt field.

The operation is entirely automatic-and does not depend upon the skill or discretion of the attendant.

The device may easily be adapted to apparatus already in operation, is simple in construction, and is effective, efiicient and rel i able.

I desire not to be limited to the precise construction and application of the invention as herein set forth, for it is evident that those skilled in the art to which this invention appertains may make various changes without departing from thespirit and scope thereof.

What ll claim is 1. in a system of motor control, the combination with a compound Wound electric motor, of starting resistance therefor, and a. device controlled by the motor for shortcircuiting said starting resistance and for closing a short-circuit around the resistance and the series field winding of the motor and introducingresistance in series With the said field winding.

2. in a system of motor control, the 001m hination with a compound wound electric motor, of a sectional starting resistance therefor, and means dependent upon the speed of the motor to short-circuit sections of the'said resistance and to close a shortcircuit around the resistance and the series field winding of the motor and introduce resistance in series with the said field winding.

3. In a system of motor control, the com bination with a compound Wound electric motor, of a sectional starting resistance in series with a field Winding of the motor, and means controlled by the motor to close short-circuits across sections of the starting resistance, to close a shortcircuit around the resistance and the series field Winding of motor, and to remove the said short circuit.

5. In a system of motor control, the combination with a compound 'wound electric motor, of sectional starting resistance in series with the series field winding of the motor, and an accelerating magnet operaresistance therefor in circuit with the series -field ,winding of the motor, and an accelerconnected across the motor armature with contacts arranged to be attracted in succes-4 sion, the two contacts last attracted being connected to the terminals of the series field winding, and a movable contact member with which the last accelerating magnet contact connects and which is operative to short-circuit the series field and the starting resistance through a path containing only one contact connection.

8. The combination with a 'compound Wound electric motor, of sectional starting resistance therefor, an accelerating magnet controlled by the motor with movable contact arms and contacts arranged to shorteircuit portions of the starting resistance, two contacts being connected to the terminals of the series field, a movable contact member to complete a connection for shortcircuiting the said portions of the starting resistance and operative when a predetermined contact arm is moved to break the said connection and to complete a shortcircuit connection around the starting resistance and theseries field.

9. The combination with a" compound Wound electric motor, of sectional starting resistance therefor, an accelerating magnet dependent for energization upon the speed of the motor and having movable contact arms with contacts arranged to short-circuit portions of the starting resistance, the

two contacts last moved being connected to the terminals of the series field, a fixed con tact member with which. the movable contacts make connection, a spring-pressed con tact member to make connection with .this

fixed contact member having also a contact to make connection with the contact on the contact arm last moved and moved by the said arm against the spring pressure to break the said connections and to establish 6::

with the said contact a short-circuit around the entire starting resistance and the series field. 10. The combination ofan acceleratingmagnet, a sectional resistance, an electroresponsive device in circuit with said resistance, means operated by said magnet for short-circuiting the sectional resistance, and means operated by the magnet to open the short circuit through saidresistance and close an additional circuit in shunt to the resistance and said electro-responsive device.

11. The combination ofan, electric motor comprising a series winding, a resistance in circuit with said winding, an accelerating magnet, and means controlled and operated by said magnet for short-circuiting said resistance, closing a circuit in shunt tosaid winding, and then opening said short-cir' cuit.

12. The combination of an electric m'o ton-comprising a series winding, resistance in the circuit of said W1nd1ng,'mea ns for .when said low resistance circuit is estabfl lished.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

DAVID LARSON.

W'itnesses EDWARD H. STEELE, GEORGE D, Rosa 

